Semiconductor device manufacturing method

ABSTRACT

A semiconductor device manufacturing method, the method including: forming an insulation layer having a protruding portion, the insulation layer having a surface and a rising surface that protrudes upward from the surface, on a semiconductor substrate; forming a conductive layer to cover the insulation layer having the protruding portion; and removing a predetermined region of the conductive layer by patterning the predetermined region according to an etching process using microwave plasma, which uses a microwave as a plasma source, while applying bias power of 70 mW/cm 2  or above on the semiconductor substrate, under a high pressure condition of 85 mTorr or above.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 14/187,609, filed on Feb. 24, 2014, which is a continuationapplication of a U.S. Ser. No. 12/673923, filed on Feb. 17, 2010, whichis a national phase entry of PCT/JP2008/065151 filed on Aug. 26, 2008and claims a priority to and the benefit of Japanese Patent ApplicationNo. 2007-226345, filed on Aug. 31, 2007, the disclosures of which areincorporated herein in its entirety by reference.

TECHNICAL FILED

The present invention relates to a semiconductor device manufacturingmethod, and more particularly, to a semiconductor device manufacturingmethod, the method including an operation of performing an etchingprocess by using plasma.

BACKGROUND ART

Semiconductor devices, such as large scale integrated circuits (LSI),are manufactured by alternately stacking an insulation layer and aconductive layer on a semiconductor substrate. Generally, a layer formedon the semiconductor substrate through a chemical vapor deposition (CVD)process, or the like is patterned according to an etching process,thereby stacking layers on the semiconductor substrate. During theetching process, plasma generated by various devices, such as a parallelplate plasma plasma source, an inductively-coupled plasma (ICP) plasmasource, and an electron cyclotron resonance (ECR) plasma source is used.

Recently, in semiconductor devices including a semiconductor element,such as a metal oxide semiconductor (MOS) transistor, a 3-dimensionalstructure is required in terms of high integration. Here, aconfiguration of a MOS transistor having a 3-dimensional structure willbe simply described.

FIGS. 12 and 13 are exterior perspective views of a semiconductor device101 including a MOS transistor having a 3-dimensional structure. FIG. 12shows a conductive layer 109, to be described later, before beingetched, and FIG. 13 shows the conductive layer 109 after being etched.Referring to FIGS. 12 and 13, the semiconductor device 101 includes aplurality of protrusions 104 that are conductive and extendperpendicularly to a main surface 103 of a semiconductor substrate(wafer) 102. Each of the protrusions 104 extends in a directionindicated by an arrow XII of FIG. 12. A source region and a drain regionare formed along a length direction of each protrusion 104, wherein theconductive layer 109 as shown in FIG. 13 is sandwiched therebetween.

An insulation layer 105 formed of SiO₂ film is formed on thesemiconductor substrate 102. Also, a thin SiO₂ film 106 is formed as agate oxide film on a channel region disposed between the source regionand the drain region so as to cover the protrusion 104. Here, since theSiO₂ film 106 constituting a gate oxide film is formed to cover theprotrusions 104, a high step XI in a layer-stacking direction existsbetween a top surface 107 of the protrusions 104, and a surface 108.

Next, the conductive layer 109 formed of polysilicon (polycrystallinesilicon) is formed to cover the SiO₂ film 106. Then, the conductivelayer 109 of polysilicon is patterned by using a resist 110 as a mask,and etched so as to remove a predetermined region of the conductivelayer 109 as shown in FIG. 13. The remaining conductive layer 109 is agate electrode. As such, the MOS transistor having a 3-dimensionalstructure is formed on the semiconductor substrate 102. Here, an etchingresidue 111 remains on sides of each protrusion 104.

Accordingly, when the etching process is performed on the conductivelayer 109 of poly-silicon having the high step XI, the etching processmay be performed in two operations having different processingconditions, as disclosed in Japanese Laid-Open Patent Publication No.hei 9-69511. Here, the etching process may be performed by a plasmaprocessing apparatus, such as the ICP plasma source, where HBr gas orCl₂ gas with a very small amount of O₂ is generally used as an etchinggas.

According to Japanese Laid-Open Patent Publication No. hei 9-69511, theetching process may be performed on the conductive layer 109 ofpoly-silicon in two operations including a main etching process and anover etching process. FIG. 14 is a graph showing a relationship betweenan etching area ratio and a etching selectivity during an etchingprocess. In FIG. 14, the horizontal axis indicates the etching arearatio (%), and the vertical axis indicates the etching selectivity(poly-silicon/SiO₂).

Here, the etching area ratio is a ratio of an area S₂ of exposedpoly-silicon to be etched with respect to the total sum of the area S₂and an area S₃ of SiO₂ exposed from the bottom layer of the poly-siliconthrough an etching process. In other words, an etching area ratio inFIG. 12 is 100, since there exists only an area S₁ of exposedpoly-silicon to be etched, and the area S₃ of the exposed SiO₂ is 0.Also, when all SiO₂ is exposed as the poly-silicon is etched out, theetching area ratio is 0. The etching selectivity is a ratio of anetching rate of poly-silicon when an etching rate of SiO₂ is 1.

Referring to FIG. 14, when SiO₂ is not exposed as in FIG. 12, the mainetching process is performed in a low etching selectivity so as toobtain an accurate shape. As the main etching process is performed, thearea S₂ of a portion to be etched decreases, and the exposed area S₃ ofSiO₂ increases. As a result, the etching residue 111 remains on thesides of each protrusion 104 as shown in FIG. 13. Here, when the etchingprocess is performed on the etching residue 111, a reaction product,such as SiBr, generated by the etching process is activated, and thereaction product deteriorates the etching selectivity. When the etchingprocess is performed in a low etching selectivity, the thin SiO₂ film106 having a large exposed area, specifically the top surface 107 of thethin SiO₂ film 106 which exists on the top surfaces of the protrusions104, may be easily damaged. Accordingly, as shown in FIG. 14, during theover etching process, the etching process needs to be performed in ahigh etching selectivity, for example, in a etching selectivity of 50 orabove.

When the etching process is performed in two steps as described above,the etching process needs to be performed in different conditions, andthus number of operations increases, thereby decreasing the efficiencyof manufacturing a semiconductor device.

DISCLOSURE OF THE INVENTION Technical Problem

To solve the above and/or other problems, the present invention providesa method of appropriately and efficiently manufacturing a semiconductordevice.

Technical Solution

According to an aspect of the present invention, there is provided asemiconductor device manufacturing method, the method including: formingan insulation layer having a protruding portion, the insulation layerhaving a surface and a rising surface that protrudes upward from thesurface, on a semiconductor substrate; forming a conductive layer tocover the insulation layer having the protruding portion; and removing apredetermined region of the conductive layer by patterning thepredetermined region according to an etching process using microwaveplasma, which uses a microwave as a plasma source, while applying biaspower of 70 mW/cm² or above on the semiconductor substrate, under a highpressure condition of 85 mTorr or above.

According to the manufacturing method of the semiconductor device, thepredetermined area of the conductive layer formed on the insulationlayer, which has the protruding portion having the rising surface, isremoved by patterning according to the etching process using microwaveplasma, in which a microwave is used as a plasma source, while applyingbias power of 70 mW/cm² or above to the semiconductor substrate underthe high pressure condition of 85 mTorr or above. Accordingly, theactivation of a reaction product generated during the etching processmay be suppressed, and the etching process may be performed whilemaintaining a high etching selectivity. As such, the etching process maybe performed while forming a shape accurately, i.e., while notgenerating an etching residue on the rising surface, and preventingdamage to the insulation layer. Also, when the semiconductor devicehaving the protruding portion is etched, the conductive layer may beremoved by performing an etching process including only one operation.Accordingly, the semiconductor device may be manufactured appropriatelyand efficiently.

In a more preferable embodiment, a bias voltage of a frequency from 100kHz to 2 MHz may be applied to the semiconductor substrate, whileperforming the etching process.

In a more preferable embodiment, a flow of an etching gas may be 1600sccm or above while performing the etching process.

In a more preferable embodiment, the insulation layer may be an oxidizedsilicon film, and the conductive layer may be a polysilicon layer.

In a more preferable embodiment, the method may further include: beforethe forming of the insulation layer, forming a conductive layer having aprotruding portion that protrudes upward on the semiconductor substrate,wherein the insulation layer may include a thin insulation layer formedon a surface of the conductive layer having the protruding portion.

In a more preferable embodiment, the insulation layer having theprotruding portion may be disposed on the top of the rising surface witha predetermined height from the surface.

According to another aspect of the present invention, there is provideda semiconductor device manufacturing method, the method including:forming a protrusion, which extends by protruding upward from a mainsurface of a semiconductor substrate and is to constitute a sourceregion and a drain region; forming an insulation layer, which is toconstitute a gate insulation film, on a channel region disposed betweenthe source region and the drain region of the protrusion; forming aconductive layer covering the protrusion and the insulation layer; andforming a gate electrode by removing the conductive layer while leavinga portion of the conductive layer on the channel region, by patterningthe conductive layer according to an etching process using microwaveplasma, which uses a microwave as a plasma source, while applying biaspower of 70 mW/cm² or above to the semiconductor substrate, under a highpressure condition of 85 mTorr or above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exterior perspective view of a semiconductor device beforean etching process is performed thereon, wherein the semiconductordevice is manufactured according to a semiconductor device manufacturingmethod of the present invention;

FIG. 2 is an exterior perspective view of the semiconductor device ofFIG. 1, viewed from a direction of an arrow II of FIG. 1;

FIG. 3 is an exterior perspective view of the semiconductor device ofFIG. 1, after an etching process is performed thereon;

FIG. 4 is an exterior perspective view of the semiconductor device ofFIG. 3, viewed from a direction of an arrow IV of FIG. 3;

FIG. 5 is a schematic diagram of a plasma processing apparatus used in asemiconductor device manufacturing method, according to an embodiment ofthe present invention;

FIG. 6 is a graph showing a relationship between pressure and a etchingselectivity;

FIG. 7 is a graph showing a relationship between bias power and aetching selectivity;

FIG. 8 is a graph showing a relationship between pressure and anelectron temperature;

FIG. 9 is a graph showing a relationship between an electron temperatureand a etching selectivity;

FIG. 10 is a graph showing a relationship between a gas flow and a taperangle;

FIG. 11 is a diagram of the semiconductor device of FIG. 4, viewed froma direction of an arrow XI of FIG. 4;

FIG. 12 is an exterior perspective view of a semiconductor deviceincluding a metal oxide semiconductor (MOS) transistor having a3-dimensional structure;

FIG. 13 is an exterior perspective view of the semiconductor device ofFIG. 12, on which an etching residue remains; and

FIG. 14 is a graph showing a relationship between an etching area ratioand a etching selectivity.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail byexplaining exemplary embodiments of the invention with reference to theattached drawings. FIGS. 1 through 4 are exterior perspective views forexplaining a semiconductor device 11 manufactured according to asemiconductor device manufacturing method of an embodiment of thepresent invention. FIG. 1 shows a conductive layer 21 before an etchingprocess is performed, and FIG. 2 shows the semiconductor device 11 ofFIG. 1, viewed from a direction of an arrow II of FIG. 1. FIG. 3 showsthe conductive layer 21 after the etching process is performed, and FIG.4 shows the semiconductor device 11 of FIG. 3, viewed from a directionof an arrow IV of FIG. 3. The semiconductor device 11 manufacturedaccording to the method of the present embodiment may be a semiconductordevice including a metal oxide semiconductor (MOS) transistor having a3-dimensional structure, and an apparatus for performing the etchingprocess may be a microwave plasma processing apparatus.

Before forming of an insulation layer, a plurality of protrusions 14formed of polysilicon and extending by protruding upward from a mainsurface 13 of a semiconductor substrate 12 are formed on thesemiconductor substrate 12, as shown in FIGS. 1 and 2. A cross-sectionof each protrusion 14 nearly has a rectangular shape. Also, eachprotrusion 14 extends in a direction indicated by an arrow I of FIG. 1.As shown in FIG. 3, a source region and a drain region are formed alonga length direction of each protrusion 14, wherein the conductive layer21, to be described later, after the etching process is sandwichedtherebetween.

Then, SiO₂ film which functions as the insulation layer 15 is formed tocover the semiconductor substrate 12, excluding the protrusions 14.Next, a thin SiO₂ film 16 (gate oxide film) is additionally formed as aninsulation layer to cover the insulation layer and the protrusions 14.Here, since the thin SiO₂ film 16, which is formed of an oxidizedsilicon, is formed to cover the protrusions 14, the SiO₂ film 16 hasprotruding portions 17 that vertically extends. In other words, the SiO₂film 16 including the protruding portions 17 includes a surface 18contacting the insulation layer 15, a rising surface 19 protrudingupward from the surface 18 and corresponding to sides of the protrudingportions 17, and a top surface 20 disposed on the top end of the risingsurface 19 with a predetermined height from the surface 18. Also, a highvertical step H is formed between the surface 18 and the top surface 20.

Then, the conductive layer 21 of poly-silicon is formed to cover theSiO₂ film 16. Patterning is performed on a portion of the conductivelayer 21 that is to be a gate electrode, by using SiN 22 as a mask.Then, as shown in FIGS. 3 and 4, the conductive layer 21 is removedthrough the etching process, while leaving the conductive layer 21 on achannel region disposed between the source region and the drain region.The remaining conductive layer 21 is a gate electrode. As such, a MOStransistor having a 3-dimensional structure is formed on thesemiconductor substrate 12.

Here, the etching process is performed by using microwave plasma,wherein a microwave is used as a plasma source, while applying biaspower of 70 mW/cm² or above on the semiconductor substrate 12, under ahigh pressure condition of 85 mTorr or above. Also, in this case, amixed gas prepared by mixing Cl₂ gas, HBr gas, and Ar gas is used as anetching gas.

According to the method of manufacturing the semiconductor device 11,when a predetermined area of the conductive layer 21 formed on theinsulation layer 15 including the protruding portions 17 having therising surface 19 is removed by patterning through the etching process,the microwave plasma, wherein a microwave is used as a plasma source, isused while applying bias power of 70 mW/cm² or above to thesemiconductor substrate 12 under a high pressure condition of 85 mTorror above. Accordingly, the activation of a reaction product generatedduring the etching process is suppressed, and the etching process may beperformed while maintaining a high etching selectivity. As such, theetching process may be performed while forming a shape accurately, i.e.,while not forming an etching residue on the rising surface 19, andpreventing damage to the SiO₂ film 16 as an insulation layer. In thiscase, specifically, the top surface 20 of the SiO₂ film 16 that ismostly exposed to the etching gas or the reaction product may beprevented from being damaged. Also, when the semiconductor device 11having the protruding portion 17 is etched, the conductive layer 21 maybe removed by performing an etching process including only oneoperation. Accordingly, the semiconductor device 11 may be appropriatelyand efficiently manufactured, since two times of etching processes as inthe conventional example doesn't need to be performed.

FIG. 5 is a schematic diagram of a plasma processing apparatus forprocessing by generating the plasma described above.

Referring to FIG. 5, the plasma processing apparatus 31 includes asealable chamber 32 for processing the semiconductor substrate 36accommodated in the plasma processing apparatus 31, and an antenna unit33 for generating plasma in the chamber 32 according to microwaves fedfrom a waveguide.

A method of performing an etching process on the semiconductor substrate36 with plasma by using the plasma processing apparatus 31 of FIG. 5will now be simply described. First, the semiconductor substrate 36 tobe processed is placed on a susceptor 34 inside the chamber 32. Next,the chamber 32 is depressurized until the pressure inside the chamber 32satisfies a discharge condition of the microwave plasma described above,and a predetermined bias voltage is applied to the semiconductorsubstrate 36. Then, microwaves are generated by a high-frequency powersupply source, and is fed to the antenna unit 33 through the waveguide.As such, plasma is generated in a plasma generating region 37 from theantenna unit 33. The generated plasma reaches a plasma diffusion region38 through a gas shower head 35, and an etching process is performed asthe plasma reacts in the plasma diffusion region 38 with a material gassupplied from the gas shower head 35.

The antenna unit 33 includes a slot plate of a disk shape having aplurality of slot holes that are each formed to have a T-shape whenviewed from below, so as to emit the microwaves fed from the waveguideto the chamber 32 through the plurality of slot holes. As such, plasmahaving a uniform electron density distribution may be generated.

Also, since, in the plasma processing apparatus 31, bias power or afrequency of a bias voltage is arbitrarily changeable, the conditions ofthe bias voltage are easily changed.

According to an example of the structure of the plasma processingapparatus 31, a distance between the susceptor 34, on which thesemiconductor substrate 36 is placed, and the antenna unit 33 may beabout 120 mm, and a distance between the susceptor 34 and the gas showerhead 35 may be about 40 mm. Also, as a discharge condition, a frequencyis 2.45 GHz. According to the plasma processing apparatus 31 having thestructure described above, when a downward distance from the antennaunit 33 to the susceptor 34 is A (mm), a range of 0≦A≦25 is the plasmagenerating region 37. Also, a range of 50≦A≦120 is the plasma diffusionregion 38. Also, an electron temperature that will be described later isa temperature in the vicinity of the surface of the semiconductorsubstrate 36 in the plasma diffusion region 38.

FIG. 6 is a graph showing a relationship between pressure and a etchingselectivity. In FIG. 6, the horizontal axis indicates pressure in mTorr,and the vertical axis indicates a etching selectivity(poly-silicon/SiO₂). Here, bias power applied to a semiconductorsubstrate is 70 mW/cm². Referring to FIG. 6, the etching selectivity isthe lowest when the pressure is 70 mTorr, and the etching selectivityincreases as the pressure increases to 80 mTorr and 90 mTorr. In thiscase, with respect to a relationship between S₂ and S₃ shown in FIG. 13,the pressure needs to be higher than at least 85 mTorr so that theetching selectivity is 50 or higher. Accordingly, during an etchingprocess, if the pressure condition is a high pressure condition of 85mTorr or above, the etching selectivity is 50 or above, therebymaintaining a high etching selectivity. As a result, a conductive layerformed of polysilicon may be removed through active etching. Morepreferably, when the pressure is 100 mTorr or higher, the etchingselectivity of 50 or above is more definitely obtained.

FIG. 7 is a graph showing a relationship between bias power and aetching selectivity. In FIG. 7, the horizontal axis indicates bias power(W), and the vertical axis indicates a etching selectivity. Asemiconductor substrate of φ300 mm will be used. In FIG. 7, ‘a’ denotesa result when the pressure is 40 mTorr, ‘b’ denotes a result when thepressure is 70 mTorr, and ‘c’ denotes a result when the pressure is 100mTorr. Referring to FIG. 7, in each pressure, when bias power isreduced, a etching selectivity is increased. However, when the biaspower is 50 W or lower, i.e., 70 mW/cm² or lower, it is difficult tocontrol a shape, and thus a side etching shape may occur as sides areetched. Accordingly, by maintaining the bias power 50 W or above, i.e.,70 mW/cm² or above, the side etching shape may be avoided. Here, theetching selectivity of 60 or above may be obtained even when the biaspower is 100 W.

Meanwhile, when the frequency of the bias voltage is too high, plasma isgenerated on the semiconductor substrate. On the other hand, when thefrequency of the bias voltage is too low, the efficiency of the biaspower decreases. Accordingly, by maintaining the frequency of the biasvoltage to be from 100 kHz to 2 MHz, such a problem may be avoided whiledecreasing the re-dissociation of a reaction product generated duringthe etching process, and thus a high etching selectivity may bemaintained.

As described above, the plasma is generated on the semiconductorsubstrate when the frequency of the bias voltage is higher than 2 MHz,but when a higher frequency of, for example from 10 MHz to 15 HMz,specifically, 13.56 MHz, is used, the dragging of ions to thesemiconductor substrate is suppressed according to the high frequency,compared to the frequency of 2 MHz, and thus damage to the semiconductorsubstrate is reduced. Accordingly, this range of frequency of the biasvoltage may be used.

FIG. 8 is a graph showing a relationship between pressure and anelectron temperature in the plasma processing apparatus shown in FIG. 5.In FIG. 8, the horizontal axis indicates pressure in mTorr, and thevertical axis indicates an electron temperature in eV. In this plasmaprocessing apparatus, the electron temperature may be 1.0 eV or lower bymaintaining the pressure to be 85 mTorr or above. More definitely, theelectron temperature may be 1.0 eV or lower by maintaining the pressureto be 100 mTorr or above.

FIG. 9 is a graph showing a relationship between an electron temperatureand a etching selectivity. In FIG. 9, the horizontal axis indicates anelectron temperature in eV, and the vertical axis indicates a etchingselectivity. Referring to FIG. 9, in order to maintain the etchingselectivity to be 50 or above, the electron temperature needs to be 1.0eV or lower. Accordingly, an etching process may be performed whilemaintaining a high etching selectivity, by setting the electrontemperature to be 1.0 eV or lower. As such, the etching process may beperformed while forming a shape accurately, i.e., while not generatingan etching residue at the side of the rising surface 19, and preventinga damage to the SiO₂ film 16 which functions as an insulation layer.Here, damage to the SiO₂ film 16, specifically, to the top surface 20that is mostly exposed to an etching gas or a reaction product, isprevented. Also, when the semiconductor device 11 having the protrudingportions 17 is etched, the conductive layer 21 may be removed by anetching process of only one operation. Accordingly, the semiconductordevice 11 may be appropriately and efficiently manufactured, since twotimes of etching processes as in the conventional example doesn't needto be performed. Also here, the electron temperature may have an error,which may be 1.05 eV or lower.

Also, preferably, a flow of an etching gas during the etching process is1600 sccm or above. FIG. 10 is a graph showing a relationship between aflow of an etching gas and a taper angle. In FIG. 10, the horizontalaxis indicates a gas flow in sccm, and the vertical axis indicates ataper angle in degrees. Here, the taper angle denotes an angle a formedbetween a sidewall 23 of the conductive layer 21 and the surface 18shown in FIG. 11. FIG. 11 is a diagram of the semiconductor device 11 ofFIG. 4, viewed from a direction of an arrow XI of FIG. 4. Referring toFIGS. 10 and 11, as the gas flow increases, the taper angle increases to90°. In other words, the sidewall 23 of the conductive layer 21protrudes upward from the surface 18, and becomes perpendicular to thesurface 18. Here, by setting the gas flow to be 1600 sccm or above, thetaper angle is closer to 90° than 88°. Also, preferably, the gas flow is2200 sccm or lower based on the capacity of a general turbo pump used inthe plasma processing apparatus.

Also, according to the above embodiments, a semiconductor devicemanufacturing method of an embodiment of the present invention, includesforming an insulation layer having the protruding portions 17 formed tocover the protrusions 14 having a cross-section that is roughly arectangular shape, but the present invention is not limited thereto. Forexample, the method may include forming an insulation layer havingprotruding portions, the insulating layer having a surface and a risingsurface that protrudes upward from the surface, wherein a cross-sectionof each of the insulation layer has a stepped shape. This is because ahigh etching selectivity is required during an etching process, since anetching residue may remain between the surface and the rising surface inthe protruding portions.

Also in the above embodiments, the above-described etching process ofthe present invention is applied to a gate etching process when aconductive layer is formed of poly-silicon and a gate electrode isformed; however the present invention is not limited thereto, and theetching process of the present invention may also be applied to a gateetching process when a conductive layer is formed of a metal layer.Examples of the metal include titanium (Ti), tantalum (Ta), and tungsten(W).

Also, in the above embodiments, an oxidized silicon (SiO₂) is used as aninsulation layer; however the present invention is not limited thereto,and an oxidized layer including hafnium (Hf), zirconium (Zr), oraluminum (Al) may be used as an insulation layer.

Also, in the above embodiments, a MOS transistor having a 3-dimensionalstructure is used as a semiconductor element; however the presentinvention is not limited thereto, and a semiconductor device having a3-dimensional structure may include a semiconductor element, such as acharge-coupled device (CCD).

While this invention has been particularly shown and described withreference to exemplary embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the invention as defined by the appended claims.

INDUSTRIAL APPLICABILITY

A semiconductor device manufacturing method according to the presentinvention is effectively used when the semiconductor device needs to beappropriately and efficiently manufactured.

1. A semiconductor device manufacturing method, the method comprising:accommodating a semiconductor substrate in a processing chamber of aplasma processing apparatus, wherein the semiconductor substrateincludes: an insulation layer having a protruding shape and having asurface that conforms to a surface of the semiconductor substrate and arising surface that protrudes upward while perpendicular to the surfaceof the insulation layer; and a conductive layer to cover the insulationlayer having the protruding shape; and patterning in the processingchamber a predetermined region of the conductive layer according to anetching process so as to remove the predetermined region and expose theinsulation layer having the protruding shape, wherein the etchingprocess is performed by microwave plasma while applying bias power of 70mW/cm² or above to the semiconductor substrate under a high pressurecondition of 85 mTorr or above, and a ratio of etching rate of theconductive layer to etching rate of the insulation layer is 50 or higherin the etching process.
 2. The method of claim 1, wherein a bias voltageof a frequency from 100 kHz to 2 MHz is applied to the semiconductorsubstrate, while performing the etching process.
 3. The method of claim1, wherein the insulation layer is an oxidized silicon film, and theconductive layer is a polysilicon layer.
 4. The method of claim 1,wherein the semiconductor substrate which is accommodated in theprocessing chamber further comprises: below the insulation layer, aconductive layer having a protruding shape that protrudes upward on thesemiconductor substrate, and the insulation layer comprises a thininsulation layer formed on a surface of the conductive layer having theprotruding shape.
 5. The method of claim 1, wherein the insulation layerhaving the protruding shape is disposed on the top of the rising surfacewith a predetermined height from the surface.
 6. The method of claim 1,wherein the semiconductor device includes a MOS transistor which has athree-dimensional structure.
 7. A semiconductor device manufacturingmethod, the method comprising: accommodating a semiconductor substratein a processing chamber of a plasma processing apparatus, wherein thesemiconductor substrate includes: a protrusion on a main surface of thesemiconductor substrate, the protrusion extending by protruding upwardwhile perpendicular to the main surface and constituting a source regionand a drain region; an insulation layer constituting a gate insulationfilm, on the protrusion including a channel region disposed between thesource region and the drain region of the protrusion; and a conductivelayer covering the protrusion and the insulation layer; and patterningin the processing chamber the conductive layer according to an etchingprocess so as to remove the conductive layer while leaving a portion ofthe conductive layer on the channel region and expose the insulationlayer having a protruding shape which conforms to an outer shape of theprotrusion, thus, forming a gate electrode, wherein the etching processis performed by microwave plasma while applying bias power of 70 mW/cm²or above to the semiconductor substrate under a high pressure conditionof 85 mTorr or above, and a ratio of etching rate of the conductivelayer to etching rate of the insulation layer is 50 or higher in theetching process.